The present invention relates to tracking catheters in fluoroscopic images, and more particularly, to tracking of a plurality of catheters simultaneously in fluoroscopic images using a novel motion compensation method to assist in atrial fibrillation ablation procedures.
Atrial fibrillation (AF) is a rapid, highly irregular heartbeat caused by abnormalities in the electrical signals generated by the atria of the heart. It is the most common cardiac arrhythmia (abnormal heart rhythm) and involves the two upper chambers (atria) of the heart. AF can often be identified by taking a pulse and observing that the heartbeats do not occur at regular intervals. However, a stronger indicator of AF is the absence of P waves on an electrocardiogram, which are normally present when there is a coordinated atrial contraction at the beginning of each heart beat. AF may be treated with medications that either slow the heart rate or revert the heart rhythm back to normal, but this treatment may be difficult and result in complications if a patient has other diseases. Synchronized electrical cardioversion may also be used to convert AF to a normal heart rhythm, but this technique is rarely been used. Surgical and catheter-based AF therapies, such as an ablation procedure, are also commonly used to treat AF.
The identification of triggers that initiate AF within the pulmonary veins (PVs) has led to prevention of AF recurrence by catheter ablation at the site of origin of the trigger. Direct catheter ablation of the triggers was traditionally limited by the infrequency with which AF initiation could be reproducibly triggered during a catheter ablation procedure. To overcome these limitations, an ablation approach was introduced to electrically isolate the PV myocardium. This segmental PV isolation technique involved the sequential identification and ablation of the PV ostium close to the earliest sites of activation of the PV musculature. This typically involved the delivery of radio frequency (RF) energy to 30% to 80% of the circumference of the PVs. The endpoint of this procedure was the electrical isolation of at least three PVs.
Catheter ablation modifies the electrical pathways of the heart in order to treat AF. In order to construct an electrical map of the heart and assist a radiofrequency ablation operation, different catheters, such as ablation, coronary sinus, and circumferential mapping catheters, are inserted in a patient's blood vessels and guided to the heart. The entire operation can be monitored with real-time fluoroscopic images. As the soft-tissue ablation targets inside the heart are not visible within the fluoroscopic images, overlay images generated from computed tomography (CT), magnetic resonance (MR), or C-arm CT can be used during the oblation procedure to facilitate more accurate catheter navigation. However, the clinical value of such overlay images is reduced by cardiac and respiratory motion.
Current technologies concentrate on gating catheter position to a fixed point in time within the cardiac cycle. Respiration effects have not been compensated. The often-advocated static positional reference provides an intermediate accuracy in association with electrocardiogram (ECG) gating. Accurate and fast tracking of catheters during the AF procedures is desirable because such tracking may increase the accuracy of model overlay by compensating respiratory motion as well as cardiac motion.